Operational notes for the Storwize family and SVC driver

In the context of OpenStack Block Storage's volume migration feature, the IBM Storwize/SVC driver enables the storage's virtualization technology. When migrating a volume from one pool to another, the volume will appear in the destination pool almost immediately, while the storage moves the data in the background.

	Note
	To enable this feature, both pools involved in a given volume migration must have the same values for extent_size. If the pools have different values for extent_size, the data will still be moved directly between the pools (not host-side copy), but the operation will be synchronous.

The IBM Storwize/SVC driver allows for extending a volume's size, but only for volumes without snapshots.

Snapshots are implemented using FlashCopy with no background copy (space-efficient). Volume clones (volumes created from existing volumes) are implemented with FlashCopy, but with background copy enabled. This means that volume clones are independent, full copies. While this background copy is taking place, attempting to delete or extend the source volume will result in that operation waiting for the copy to complete.

The IBM Storwize/SVC driver enables you to modify volume types. When you modify volume types, you can also change these extra specs properties:

	Note
	When you change the rsize, grainsize or compression properties, volume copies are asynchronously synchronized on the array.

	Note
	To change the iogrp property, IBM Storwize/SVC firmware version 6.4.0 or later is required.